PROJECT SUMMARY Eluciding the structural organization of macromolecules or molecular complexes is one of the fundamental steps towards mechanistic understanding of their function and activity regulation. With atomic level details elucided by traditional structural biology techniques such as crystallography, nuclear magnetic resonance and cryo-electron microscopy, the next step is to place this structural information in to the cellular context. For this purpose, we take the approach of using super-resolution fluorescence microscopy to map the spatial coordinates of their individual components. For this approach, we plan to develop a scalable method for efficient alabeling endogenous proteins for super-resolution microscopy, as well as analysis algorithms for super-resolution images. We will apply this approach to the study of basal body - cilium transition zone, which has been shown in our preliminary study to be a gate structure that regulates protein trafficking in the cilium.